1. Field of the Invention
The present invention relates to wireless communications; more specifically, wireless data communications.
2. Description of the Prior Art
Cellular and PCS (Personal Communication Service) communications are typically based on a frequency division duplex (FDD) system. In this type system, one range of frequencies is used for communications from a base station to a mobile terminal (forward link), and another range of frequencies is used for communications from the mobile terminal to the base station (reverse link). FIG. 1 illustrates a conventional cellular FDD channel plan. Reverse link band 10 and forward link band 12 are divided into subbands labeled A and B. Typically, a different service provider provides service in each of the lettered bands. In the case of cellular communications in the United States, the reverse link band ranges from 824 MHz to 849 MHz, and the forward link band ranges from 869 MHz to 894 MHz. Each of the subbands are broken up into narrow band channels of 30 KHz in analog, TDMA, and CDPD systems, 1.22 MHz in CDMA systems, and 200 KHz in GSM systems. The narrow band channels are paired so that for a particular communication session between a mobile terminal and a base station, a narrow band reverse channel and narrow band forward channel are available. When data communications are implemented over cellular communication links, such as narrow band 30 KHz links relatively slow data transfer rates of 4.8 to 13.3 Kbits/sec are achieved.
FIG. 2 illustrates the United States PCS spectrum. As with the cellular, there is a reverse link band 50 and a forward link band 60. Each of the reverse link and forward link bands are broken into subbands labeled A, B, C, D, E and F, where a different service provider is licensed for operations in each of the subbands. In the case of the reverse link band, the band ranges from 1850 MHz to 1910 MHz, and in the case of the forward link band, the range is from 1930 MHz to 1990 MHz. As with the cellular band, pairs of channels are used for communications between a base station and a mobile terminal. In this case, however, if a CDMA (Code Division Multiple Access) system is used, the channel pairs have 1.25 MHz bandwidths. It should be noted, it is also possible to use TDMA (Time Division Multiple Access) systems for these types of communications. Systems such as CDMA systems offer an advantage over typical cellular systems in that the communication band for both the forward and reverse links are 1.25 MHz wide which allows a faster data transfer. Unfortunately, even a 1.25 MHz wide channel does not provide sufficient bandwidth for the timely transfer for large amounts of data. For example, a 1.25 MHz channel provides 9.6 to 13.3 Kbits/sec.
The present invention provides high speed data transfer from a base station to a mobile terminal using an additional wide band communication channel that supplements the communications provided by the reverse (mobile to base station) and forward (base station to mobile) links used in-cellular or PCS (Personal Communication Service) communications systems. In one embodiment, the standard forward and reverse links are used as control channels for data transfers over the additional or adjunct forward wide band channel as well as for voice and/or low speed data traffic. In another embodiment, the communications carried out over the narrow band forward link channel are sent over the adjunct wide band forward channel thereby eliminating the need for a narrow band forward link channel.